Forum OpenACS Q&A: unable to delete unmounted application

I am going through the templating tutorial. I've installed the package notes and at first it didn't work properly. It works ok now (under notes-2), but I am still left with this unmounted application (notes-1) which I don't seem to get rid of. I get the following error when trying to delete it:

Request Error

Database operation "0or1row" failed (exception NSDB, "Query was not a statement returning rows.")
    while executing
"ns_pg_bind 0or1row nsdb0 {
      
        select case when count(*) = 0 then 0 else 1 end from apm_packages
        where package_id = :package_id
    
      }"
    ("uplevel" body line 1)
    invoked from within
"uplevel $ulevel [list ns_pg_bind $type $db $sql"
    invoked from within
"db_exec 0or1row $db $full_name $sql"
    invoked from within
"set selection [db_exec 0or1row $db $full_name $sql]"
    ("uplevel" body line 2)
    invoked from within
"uplevel 1 $code_block "
    invoked from within
"db_with_handle db {
        set selection [db_exec 0or1row $db $full_name $sql]
    }"
    (procedure "db_string" line 7)
    invoked from within
"db_string instance_delete_doubleclick_ck {
        select decode(count(*), 0, 0, 1) from apm_packages
        where package_id = :package_id
    } -default 0"
    ("uplevel" body line 1)
    (procedure "db_transaction" line 1)
    invoked from within
"db_transaction {
    db_exec_plsql package_instance_delete {
        begin
        apm_package.delete(package_id => :package_id);
        end;
    }
} on_error {
    if {[..."
    ("uplevel" body line 26)
    invoked from within
"uplevel {
          ad_page_contract {

    Delete an unmounted package instance.

    @author Bryan Quinn (bquinn@arsdigita.com)
    @creation-date Mon ..."
    (procedure "code::tcl::/web/bradutcom/packages/acs-subsite/www/admin/sit..." line 2)
    invoked from within
"code::tcl::$__adp_stub"
    invoked from within
"if { [file exists $__adp_stub.tcl] } {

      # ensure that data source preparation procedure exists and is up-to-date
      adp_init tcl $__adp_stub
..."
    ("uplevel" body line 3)
    invoked from within
"uplevel {

    if { [file exists $__adp_stub.tcl] } {

      # ensure that data source preparation procedure exists and is up-to-date
      adp_init t..."
    (procedure "adp_prepare" line 3)
    invoked from within
"adp_prepare "
    (procedure "template::adp_parse" line 30)
    invoked from within
"template::adp_parse [file root [ad_conn file]] {}"
    (procedure "adp_parse_ad_conn_file" line 7)
    invoked from within
"$handler"
    ("uplevel" body line 2)
    invoked from within
"uplevel $code"
    invoked from within
"ad_try {
        $handler
      } ad_script_abort val {
        # do nothing
      }"
    invoked from within
"rp_serve_concrete_file [ad_conn file]"
    (procedure "rp_serve_abstract_file" line 60)
    invoked from within
"rp_serve_abstract_file "$root/$path""
    ("uplevel" body line 2)
    invoked from within
"uplevel $code"
    invoked from within
"ad_try {
        rp_serve_abstract_file "$root/$path"
        set tcl_url2file([ad_conn url]) [ad_conn file]
        set tcl_url2path_info([ad_conn url]) [ad_conn path_inf..."

thanks for your help